1. Field of Invention
The present invention relates to a disc device, in particular, to a disc device having a part containing a disc, which part can be drawn from/inserted in to the disc device. One example of such a disc device is a CD-ROM drive device which may be incorporated into a notebook type personal computer or the like.
2. Description of Related Art
A compact disc, having a diameter of 12 cm or 8 cm, serving as an information recording medium, has been being used for recording, for example, data base, software program or the like. Such information recorded on a compact disc will be reproduced using a laser type pick up. The above-mentioned CD-ROM drive device is used to handle the compact disc used as a ROM. Such a compact disc is called a CD-ROM. The CD-ROM drive device has been developed to be incorporated into a notebook type personal computer. The notebook type personal computer is a miniaturized personal computer. In the above-mentioned development, the CD-ROM drive device is developed to be incorporated into a given case.
One example of such a CD-ROM drive device in the related art incorporated into a notebook type personal computer or the like will now be described. A CD-ROM drive body of the CD-ROM drive device is contained in a containing portion formed in a personal computer body. When the CD-ROM is loaded on the CD-ROM drive body or a once loaded CD-ROM is removed from the CD-ROM drive body, the CD-ROM drive body itself is drawn from the personal computer body.
A push-on/push-off mechanism is used between the CD-ROM drive device and the above-mentioned containing portion formed in the personal computer body. By using the push-on/push-off mechanism, the CD-ROM drive body can be locked in the containing portion when an operator pushes the CD-ROM drive body. Further, the locking of the CD-ROM drive body in the containing portion can be released so that the CD-ROM drive body can be drawn from the personal computer, when the operator pushes the CD-ROM drive body. If the CD-ROM drive body can be drawn from the containing portion at any time, a problem may occur. That is, if the CD-ROM drive body is drawn from the containing portion, that is, it is drawn from the personal computer, during the CD-ROM being rotated by means of a spindle motor and/or an optical head accessing the CD-ROM, an operator's hand may, by accident, touch the CD-ROM being rotated.
In order to eliminate such a problem, a locking mechanism having an electrically operating interlocking function has been used instead of the above-described push-on/push-off mechanism. If such a locking mechanism is used, an operator performs an ejecting operation. As a result of the ejecting operation being performed, the rotation of the CD-ROM is stopped and also the optical head is removed from the CD-ROM. The above-mentioned locking of the CD-ROM drive body in the containing portion is then released after the rotation of the CD-ROM has been stopped and also the optical head has been removed from the CD-ROM.
With reference to FIG.1, the CD-ROM drive device 81 in the related art having such a locking mechanism will now be described. The CD-ROM drive device 81, due to the locking mechanism, releases the locking of the CD-ROM drive body in the containing portion after an operation in the CD-ROM drive device has been stopped. The CD-ROM drive device 81 includes the flat rectangular parallelopiped CD-ROM drive body 82. The CD-ROM drive body 82 has a turn table 83, a spindle motor (not shown in the figure) for rotating the turn table 83, the optical head 84, an optical head moving mechanism (not shown in the figure) and so forth provided therein. Further, a locking mechanism 91 for locking the CD-ROM drive body 82 in the containing portion 73 and releasing the locking is provided in the CD-ROM drive device 81.
The CD-ROM drive body 82 is slidable along directions A.sub.1 (rear direction) and A.sub.2 (front direction) shown in FIG. 1 with respect to the containing portion 73 formed in the personal computer body 71. FIG. 1 shows a state where the CD-ROM drive body 82 is contained in the containing portion 73. A front panel 85 is provided in front of the CD-ROM drive body 82 as shown in the figure. In this state, the front end of the front panel 85 is approximately aligned with a front surface of the personal computer body 71 along a direction perpendicular to the directions A.sub.1 and A.sub.2.
The locking mechanism 91 is consists of a plunger 92, a locking arm 94 and a spring 95, they being located at a rear portion of the containing portion 73, and a locking pin 97 formed on the CD-ROM 30 drive body 82. When no electric current is supplied to the plunger 92, the locking arm 94 is forced to turn about a shaft S counterclockwise in the figure by means of the spring 95. An iron core 93 provided as a part of the plunger 92 is movable along directions E.sub.1 and E.sub.2 shown in the figure. When an electric current is supplied to the plunger 92, the iron core 93 is forced to move in the direction E.sub.2 as a result of an electric magnet provided in the plunger 92 attracting the iron core 93.
In a state where the CD-ROM drive body 82 is contained in the containing portion 73, no electric current is supplied to the plunger 92. Therefore, an end portion 94a of the locking arm 94 engages with the locking pin 97 as shown in FIG. 1. Thus, the CD-ROM drive body 82 is locked in the containing portion 73 and thus the CD-ROM drive body 82 cannot be drawn in the direction A.sub.2.
When the ejecting operation is performed by the operator, an electric current is supplied to the plunger 92 and thus the electric magnet of the plunger 92 attracts the iron core 93 in the direction E.sub.2, the iron core 93 thus moving in the direction. As a result, a projecting end of the iron core 93 pushes a end portion 94b of the locking arm 94 and thus the locking arm 94 is rotated clockwise. Thereby, the end portion 94a is removed from the locking pin 97 and thus the locking of the CD-ROM drive body 82 in the containing portion 73 is released. A pushing mechanism (not shown in the figure) then pushes the CD-ROM drive body 82 in the direction A.sub.2 for a predetermined stroke. Thus, the operator may pull the front panel 85 of the CD-ROM drive body 82 and draw the CD-ROM drive body 82 from the containing portion 73 in the direction A.sub.2.
In order to make the thus-drawn CD-ROM drive body 82 again be contained in the containing portion 73, an operator may push the CD-ROM drive body 82 in the direction A.sub.1. Thus, the end portion 94a of the locking arm 94 engages with the locking pin 97 and thus the CD-ROM drive body 82 is again locked in the containing portion 73.
A CD-ROM drive device 100 in another example in the related art being provided with a locking mechanism 101 including a motor 102 and a group of cams 103 will now be described, with reference to FIG. 2. The same reference numerals, as those of the components in the CD-ROM drive device 81 shown in FIG.1, are given to components in the CD-ROM drive device 100 identical to the components in the device 81.
The locking mechanism 101 includes the motor 102, the group of cams 103, a locking arm 104 and a spring 106. The locking pin 97 is formed on the CD-ROM drive body 82. When no electric current is supplied to the motor 102, the locking arm 104 is formed to be rotated about a shaft 105 clockwise by means of the spring 106.
In a state where the CD-ROM drive body 82 is contained in the containing portion 73, no electric current is supplied to the motor 102. Therefore, an end portion 104a of the locking arm 104 engages with the locking pin 97 as shown in FIG. 2. Thus, the CD-ROM drive body 82 is locked in the containing portion 73 and thus the CD-ROM drive body 82 cannot be drawn in the direction A.sub.2.
When the ejecting operation is performed by the operator, an electric current is supplied to the motor 102 and thus the motor 102 rotates cam gears 103b and 103a. As a result, a cam pin 107 presses an end portion 104b of the locking arm 104. Thus, the locking arm 104 is rotated counterclockwise. Thereby, the end portion 104a is removed from the locking pin 97 and thus the locking of the CD-ROM drive body 82 in the containing portion 73 is released. A pushing mechanism (not shown in the figure) then pushes the CD-ROM drive body 82 in the direction A.sub.2 for a predetermined stroke. Thus, the operator may pull the front panel 85 of the CD-ROM drive body 82 and draw the CD-ROM drive body 82 from the containing portion 73 in the direction A.sub.2.
However, either of the CD-ROM drive devices in the related art shown in FIGS. 1 and 2 needs a space for containing the locking mechanism 91 or 101 behind the CD-ROM drive body 82. Thereby, miniaturizing of the CD-ROM drive device including the containing portion 73 and thinning of the CD-ROM drive device is limited. From another point of view, if the entire volume of the CD-ROM drive device is fixed, such a space for containing the locking mechanism 91 or 101 restricts a space required for containing other attachments of the CD-ROM drive device such as an electric circuit substrate, a flexible wire and so forth.
With reference to FIGS. 3, 4 and 5, a CD-ROM drive device 161 in another example in the related art will now be described. FIG.4 shows a front elevational view of the device 161 but a front panel 172 is omitted in FIG. 4. FIG. 5 shows a left side elevational view of the device 161. The CD-ROM drive device 161 includes a containing portion 162 fixed in a personal computer body and a CD-ROM drive body 171 movable with respect to the containing portion 162 along directions A.sub.1 and A.sub.2 shown in FIGS. 3 and 5.
The CD-ROM drive body 171 includes a flat rectangular parallelopiped housing 173. The housing 173 has the turn table 185, the spindle motor (not shown in the figure) for rotating the turn table 185, the optical head 186, the optical head moving mechanism (not shown in the figure) and so forth provided therein. The housing 173 further has the front panel 172 fixed thereon. Further, the locking mechanism for locking the CD-ROM drive body 171 in the containing portion 162 and releasing the locking is provided in the CD-ROM drive device 161. The locking mechanism used in the device 161 comprises, for example, the above-described push-on/push-off mechanism.
A top plate 173a of the housing 173 has an opening 173d formed therein. The turn table 185 projects from a top surface 173a through the opening 173d as shown in FIG. 3, the CD-ROM 51 being placed on the turn table 185. The optical head 186 is exposed via the opening 173d as shown in FIG. 3, the optical head 186 directing upward.
Side plates 164 and 165 have rail members 181 and 182 fixed thereon respectively. Each of the rail members 181 and 182 extends along the directions A.sub.1 and A.sub.2 and has an angular letter "C"-shaped section as shown in FIG. 4. Side plates 173b and 173c of the housing 173 of the CD-ROM drive body 171 have guides 175 and 176 formed thereon respectively. Each of the guides 175 and 176 is shaped so that a sectional view thereof includes a protrusion which is fitted into a groove formed on a respective one of the rail members 181 and 182 as shown in FIG. 4. The thus-shaped guides 175 and 176 are slidable on the rail members 181 and 182 respectively in a state in which the protrusions of the guides 175 and 176 are fitted into the grooves of the rail members 181 and 182 respectively.
As the guides 175 and 176 being guided by the rail members 181 and 182 respectively, the CD-ROM drive body 171 is movable with respect to the containing portion 162 along the directions A.sub.1 and A.sub.2. FIG. 3 shows a state in which the CD-ROM drive body 171 has been drawn from the containing portion 162 to the limit.
In a state in which the CD-ROM drive body 172 is contained in the containing portion 162, the locking mechanism locks the CD-ROM drive body 171 in the containing portion 162. Thus, drawing of the CD-ROM drive body 171 in the direction A.sub.2 is prevented. In this state, the protrusions of the guides 175 and 176 are fitted into the grooves of the rail members 181 and 182 through the entire length thereof along the directions A.sub.1 and A.sub.2.
When the ejecting operation is performed by an operator, the locking of the CD-ROM drive body 171 in the containing portion 162 performed by the locking mechanism is released. After that, the operator may draw the CD-ROM drive body 171 from the containing portion 162 in the direction A.sub.2 by pulling the front panel 172. As shown in FIGS. 3 and 5, in the state where the CD-ROM drive body 171 has been drawn from the containing portion 162 to the limit, the protrusions of the guides 175 and 176 engage with the grooves of the rail members 181 and 182 for a length of L.sub.1 along the directions A.sub.1 and A.sub.2 shown in the figures at the rear end of the CD-ROM drive body 171.
In the CD-ROM drive device 161 in the related art shown in FIGS. 3, 4 and 5, a length along the directions A.sub.1 and A.sub.2 for which the protrusions of the guides 175 and 176 engage with the grooves of the rail members 181 and 182 becomes shorter as the CD-ROM drive body 171 is drawn from the containing portion 162. Dimensions of the CD-ROM drive body 171 and those of the containing portion 162 are the minimum ones in order to miniaturize the CD-ROM drive device 161. As a result, the above-mentioned engaging length L.sub.1 shown in FIGS. 3 and 5 is inevitably shortened to be approximately 10% of the entire length of each of the guides 175 and 176.
Further, there are appropriate clearances between each of the guides 175 and 176 and a respective one of the rail members 181 and 182 such that the CD-ROM drive body 171 is slidable in the containing portion 162 along the directions A.sub.1 and A.sub.2. By these clearances, the CD-ROM drive body 171 may undesirably move with respect to the containing portion 162 along directions other than along the directions A.sub.1 and A.sub.2. Lengths of such possible undesirable movement increase as the length in the directions A.sub.1 and A.sub.2 for which the guides 175 and 176 engage with the rail members 181 and 182 is shortened.
That is, the lengths of such possible undesirable movement increase as the CD-ROM drive body 171 is drawn from the containing portion 162 to the limit. The possible undesirable movement has the maximum moving lengths when the CD-ROM drive body 171 has been drawn from the containing portion 162 to the limit. The possible undesirable movement includes movement in vertical directions Z.sub.1 and Z.sub.2 shown in FIGS. 4 and 5 and movement in horizontal directions B.sub.1 and B.sub.2 shown in FIGS. 3 and 5. In the structure shown in FIGS. 3, 4 and 5, assuming that a drawn length of the CD-ROM drive body 171 is 120 mm when it has been drawn to the limit and then the above-mentioned length L.sub.1 is 10 mm, an front end of the CD-ROM drive body 171 may move for approximately 4 mm in the vertical directions.
In a disc device, such as the CD-ROM drive device, in the related art, a tray such as the CD-ROM on which a disc such as the CD-ROM is placed is driven by a motor. When the tray has been drawn from a chassis of the disc device, an operator may place the disc on a turn table provided in the tray. The motor then drives the tray having the disc placed on the turn table to be returned inside the chassis. Then, the disc is clamped onto the turn table.
Such a CD-ROM drive device has the motor and a power transmission mechanism for transmitting driving power of the motor to the tray provided therein. Due to a space for containing the motor and the power transmission mechanism, miniaturizing of the CD-ROM drive device and thinning of the CD-ROM drive device is limited. Therefore, it is not possible to incorporate such a CD-ROM drive device into a notebook type personal computer.
In order to eliminate such a problem, a disc device, such as the CD-ROM drive device, which does not include the motor and the power transmission mechanism has been being developed. In such a disc device, the tray is manually moved so that either the tray is inserted in the chassis for an operator to use the disc as an information recording medium or the tray is drawn from the chassis for the operator to replace the disc on the tray. A position of the tray which is obtained as a result of the tray being inserted into the chassis so that the operator can use the disc as an information recording medium will be referred to as a loaded position, hereinafter. A position of the tray which is obtained as a result of the tray being drawn from the chassis so that the operator can replace the disc on the tray will be referred to as a replaceable position, hereinafter.
A disc device in an example in the related art such as the device mentioned above in which the tray is manually moved will now be described. The tray is supported on a sub-chassis which has guide rails provided on two sides thereof. Due to a function of the guide rails of the sub-chassis, the sub-chassis is movable with respect to the chassis of the disc device. Thus, the tray is movable with respect to the chassis. The turn table and a pick up are mounted to a base which is mounted to the sub-chassis. Because the turn table and the pick up are precision components, it is necessary to prevent any vibrations occurring in the sub-chassis from being applied to the turn table and pick up. For this purpose, a rubber-made vibration absorbing member for absorbing vibrations is inserted between the base and the sub-chassis.
However, in the above-described structure, because the tray is directly mounted on the sub-chassis, vibrations occurring in the sub-chassis are directly transmitted into the tray. Further, part of these vibrations are also transmitted to the turn table and pick up via the vibration absorbing member and the base. Because the vibration absorbing member is provided only between the sub-chassis and the base, the turn table and the pick up vibrate periodically in a period different from a period in which the tray vibrates periodically. If a relatively large vibration occurs in the sub-chassis, the rubber-made vibration absorbing member may be elastically deformed in a large deformation length. In such a case, the turn table and pick up may vibrate violently and thus the disc clamped onto the turn table may come into contact with the tray. If the disc come into contact with the tray, the disc may be damaged.
Similarly, due to the vibration of the turn table, the turn table may come into contact with a top plate. The top plate is a plate which cover a top side of the chassis of the disc device. The top plate is located over the turn table, when the tray is in the above-mentioned loaded position. In order to prevent the turn table from coming into contact with the top plate, it is necessary to position the top plate an appropriate clearance away from the turn table. However, this result in limiting miniaturizing of the disc device and thinning thereof.
In a disc device in the related art, the tray has outer dimensions such that the entire outer diameter of the disc can be placed on the tray. Specifically, the tray has a concavity formed thereon which contains the disc. Such a structure of the tray limits miniaturizing of the tray and thus limits miniaturizing of the disc device.